<template>
    <section class="bg-body">
        <div class="context">
            <h1>Css 背景动画</h1>
        </div>
        <div class="area">
            <ul class="circles">
                <li></li>
                <li></li>
                <li></li>
                <li></li>
                <li></li>
                <li></li>
                <li></li>
                <li></li>
                <li></li>
                <li></li>
            </ul>
        </div>
    </section>
</template>

<script>
    export default {
        name: "css-bg"
    }
</script>

<style scoped>
    * {
        margin: 0px;
        padding: 0px;
    }

    .bg-body {
        font-family: 'Exo', sans-serif;
        height: 800px;
        overflow: hidden;
        border-radius: 8px;
    }

    .context {
        width: 100%;
        position: absolute;
        top: 50vh;

    }

    .context h1 {
        text-align: center;
        color: #fff;
        font-size: 50px;
    }

    .area {
        background: #4e54c8;
        background: -webkit-linear-gradient(to left, #8f94fb, #4e54c8);
        width: 100%;
        height: 100vh;
    }

    .circles {
        position: absolute;
        top: 0;
        left: 0;
        width: 100%;
        height: 100%;
        overflow: hidden;
    }

    .circles li {
        position: absolute;
        display: block;
        list-style: none;
        width: 20px;
        height: 20px;
        background: rgba(255, 255, 255, 0.2);
        animation: animate 25s linear infinite;
        bottom: -150px;

    }

    .circles li:nth-child(1) {
        left: 25%;
        width: 80px;
        height: 80px;
        animation-delay: 0s;
    }

    .circles li:nth-child(2) {
        left: 10%;
        width: 20px;
        height: 20px;
        animation-delay: 2s;
        animation-duration: 12s;
    }

    .circles li:nth-child(3) {
        left: 70%;
        width: 20px;
        height: 20px;
        animation-delay: 4s;
    }

    .circles li:nth-child(4) {
        left: 40%;
        width: 60px;
        height: 60px;
        animation-delay: 0s;
        animation-duration: 18s;
    }

    .circles li:nth-child(5) {
        left: 65%;
        width: 20px;
        height: 20px;
        animation-delay: 0s;
    }

    .circles li:nth-child(6) {
        left: 75%;
        width: 110px;
        height: 110px;
        animation-delay: 3s;
    }

    .circles li:nth-child(7) {
        left: 35%;
        width: 150px;
        height: 150px;
        animation-delay: 7s;
    }

    .circles li:nth-child(8) {
        left: 50%;
        width: 25px;
        height: 25px;
        animation-delay: 15s;
        animation-duration: 45s;
    }

    .circles li:nth-child(9) {
        left: 20%;
        width: 15px;
        height: 15px;
        animation-delay: 2s;
        animation-duration: 35s;
    }

    .circles li:nth-child(10) {
        left: 85%;
        width: 150px;
        height: 150px;
        animation-delay: 0s;
        animation-duration: 11s;
    }

    @keyframes animate {
        0% {
            transform: translateY(0) rotate(0deg);
            opacity: 1;
            border-radius: 0;
        }
        100% {
            transform: translateY(-1000px) rotate(720deg);
            opacity: 0;
            border-radius: 50%;
        }
    }
</style>
